US10214974B2ActiveUtilityPatentIndex 41
System for compensating heaving for an element hooked onto movable equipment
Est. expiryOct 20, 2034(~8.3 yrs left)· nominal 20-yr term from priority
Inventors:MABILE CLAUDE
E21B 19/09B66C 13/02E21B 19/002B66D 1/52B66C 13/52E21B 19/006B63B 27/30
41
PatentIndex Score
0
Cited by
15
References
18
Claims
Abstract
The present invention relates to a motion compensation system for an element hanging from a mobile unit, the system comprising two blocks, at least two articulated arms, a compensation cylinder and a cable. According to the invention, at least one characteristic length of the articulated system (for example: the length of a link or the distance between two sheaves of two articulated arms) is adjusted according to the motion to be compensated for.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1. A motion compensation system for an element hanging from a mobile unit, said system comprising a first block and a second block for hanging said element, said first block being connected to said mobile unit by at least two articulated arms, each articulated arm comprising an idler sheave connected to said mobile unit, an intermediate sheave, a first link between said idler sheave and said intermediate sheave, and a second link between said intermediate sheave and said first block, said system comprising a cable fastened to retaining means and running through the idler sheave and the intermediate sheave of each of said articulated arms and through said first and second blocks, said system further comprising at least one compensation cylinder linked to said first block and to said mobile unit, and a means for adjusting at least one characteristic length of said articulated arms according to motion of said mobile unit, the at least one characteristic length is at least one of a horizontal distance between the axis of first block and the axis of idler sheave, a length of the first link or the second link, a vertical distance between a lower position of an axis of a sheave of the first block and the axis of the idler sheave.
2. The system as claimed in claim 1 , wherein said adjusted characteristic length is length that minimizes an error function defined by a formula of the form:
E
=
Fm
-
Fa
Fm
with
Fm
Q
=
1
+
[
sin
(
θ
+
φ
)
+
sin
(
β
)
-
sin
(
θ
+
σ
-
φ
)
sin
(
θ
-
φ
)
sin
(
θ
)
]
1
N
+
U
Q
a
nd
a
=
(
Q
+
U
)
V
0
γ
(
V
0
+
(
De
-
De
0
)
S
)
γ
,
with:
φ: angle between the axis of the first link and the horizontal,
θ: angle between the axis of the second link and the horizontal,
β: angle between the cable and the axis of the first link,
σ: angle between the cable and the axis of the second link,
Fm: mechanical force on the compensation cylinder,
Q: weight of the hanging element,
U: constant related to the design of the system, corresponding to the sum of the weight of the first block, of the compensation cylinder rocks and of the articulated arms,
Fa: pressure variation in the compensation cylinder,
De: compensation cylinder stroke, with De 0 the initial stroke,
V 0 : reference volume of the compensation cylinder,
N: number of sheaves,
S: section of an accumulator equipping said compensation cylinder,
Γ: gas constant,
E: error function.
3. The system as claimed in claim 1 , wherein said idler sheave is connected to said mobile unit by a controlled means of adjustable length.
4. The system as claimed in claim 1 , wherein at least one of said links comprises a hydraulic, pneumatic or electric cylinder controlled in position.
5. The system as claimed in claim 1 , wherein only a length of a link or only distance between the axes of said sheaves is controlled.
6. The system as claimed in claim 1 , wherein said first and second blocks are vertically aligned and said motion is vertical.
7. The system as claimed in claim 1 , wherein said mobile unit is an offshore unit, notably a ship.
8. The system as claimed in claim 7 , wherein said element is a drill bit or a riser pipe or a parcel laying tool.
9. The system as claimed in claim 1 , wherein said compensation cylinder is a pneumatic cylinder fed by at least one accumulator.
10. The system as claimed in claim 1 , wherein said means for retaining cable comprise at least one winch.
11. A drill bit support comprising the motion compensation system as claimed in claim 1 .
12. A riser pipe comprising the motion compensation system as claimed in claim 1 .
13. An offshore blowout preventer comprising the motion compensation system as claimed in claim 1 .
14. A motion compensation system for an element hanging from a mobile unit, the system comprising a first block and a second block for hanging the element, the first block being connected to the mobile unit by at least two articulated arms, each articulated arm comprising an idler sheave connected to said mobile unit, an intermediate sheave, a first link between said idler sheave and said intermediate sheave, and a second link between said intermediate sheave and said first block, the system comprising a cable fastened to retaining means and running through the idler sheave and intermediate sheave of each of the articulated arms and through the first and second blocks; at least one compensation cylinder linked to the first block and to said mobile unit; and an adjustable cylinder of adjustable length for adjusting at least one characteristic length of the articulated arms according to motion of the mobile unit, the at least one characteristic length is at least one of a horizontal distance between the axis of first block and the axis of idler sheave, a length of the first link or the second link, a vertical distance between a lower position of an axis of a sheave of the first block and the axis of the idler sheave.
15. The system as claimed in claim 14 , wherein the adjustable cylinder comprises a pneumatic cylinder, a hydraulic cylinder or an electric cylinder connected between the mobile unit and the at least one sheave of at least one of the articulated arms.
16. A drill bit support comprising the motion compensation system as claimed in claim 14 .
17. A riser pipe comprising the motion compensation system as claimed in claim 14 .
18. An offshore blowout preventer comprising the motion compensation system as claimed in claim 14 .Cited by (0)
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